A Higher-Order Period Function and Its Application. - Linping Peng; Lianghaolong Lu; Zhaosheng Feng (Int. J. Bifurc. Chaos, 2015)

Number of Critical Periods for Perturbed Rigidly Isochronous Centers. - Lianghaolong Lu; Linping Peng; Zhaosheng Feng (Int. J. Bifurc. Chaos, 2016)